NbMC LAYERS

ABSTRACT

Methods of forming thin-film structures including one or more NbMC layers, and structures and devices including the one or more NbMC layers are disclosed. The NbMC layers enable tuning of various structure and device properties, including resistivity, current leakage, and work function.

FIELD OF THE INVENTION

The present disclosure generally relates to techniques for formingstructures including one or more niobium metal or metalloid carbide(NbMC) layers, to devices including the one or more niobium metal ormetalloid carbide layers, and to methods of forming the structures anddevices.

BACKGROUND OF THE DISCLOSURE

Field-effect transistor (FET) devices, such as metal-oxide-semiconductorFET (MOSFET) devices generally include a source region, a drain region,a channel region between the source and drain regions, and a gateelectrode overlying the channel region and separated from the channelregion by a dielectric material. A complimentary MOSFET (CMOS) deviceincludes a p-type MOSFET device and an n-type MOSFET device. There arealso three-dimensional transistor architectures like FinFET's. Tooperate as desired, a work function of the gate electrode of the n-typedevice and of the p-type device must differ by a certain amount. Thedifference in the work function is generally obtained by tuning the gateelectrode material.

Traditionally, MOSFET devices are formed using silicon oxide as thedielectric material and polysilicon as the gate electrode material.Polysilicon has worked relatively well as a gate electrode material,because it allows relatively easy tuning of a work function of thedevices and consequently a threshold voltage of the devices.

As MOSFET devices are scaled down to meet desired performance criteria,metal has generally replaced polysilicon as a gate electrode materialand high dielectric constant material has generally replaced siliconoxide as the dielectric material for high performance devices. However,by replacing polysilicon with metal, a work function difference betweenthe gate and the channel becomes more difficult to tune. As a result,modification of a threshold voltage of the device becomes moredifficult.

To facilitate work function tuning of MOSFET devices including a metalgate electrode, gate structures can include an additional metal layer,i.e., a work function layer, to tune the work function and consequentlythe threshold voltage of the devices. Generally, the work-functionlayers are relatively less conductive than gate electrode metal, whichcan result in a loss of desired performance of the devices. Attempts toincrease the conductivity of the work-function layers generally resultsin lower work function of the devices.

Accordingly, improved material layers suitable for tunable work functionlayers and structures and devices including such layers as well asmethods of forming such layers, structures, and devices are desired.

SUMMARY OF THE DISCLOSURE

Various embodiments of the present disclosure relate to methods offorming structures and devices including one or more niobium metaland/or metalloid carbide (collectively referred to herein as NbMC, whereM represents a metal and/or metalloid) layers or films and to structuresand devices including NbMC layers. In general, embodiments of thedisclosure provide methods of forming structures and devices with one ormore NbMC tunable work function layers that exhibit relatively lowresistivity and/or that are relatively easy to tune. Additionally,exemplary devices and structures including NbMC layers exhibitrelatively low work functions and the work function of such devices andstructures can be tuned over a relatively wide range. Further, exemplaryNbMC layers can exhibit relatively high oxidation resistance, relativeto other material layers used as work function or similar layers. Thefilms are just recited with acronym NbMC for simplicity reasons forfilms comprising niobium, metal or metalloid and carbon and acronym NbMCdoes not limit, for example, the stoichiometry of the films or bondingtypes in the films or bonding between atoms.

Various other embodiments of the disclosure relate to a method offorming a thin-film structure, wherein the method includes providing asubstrate within a reaction space and using a first cyclic depositionprocess, forming a layer comprising NbMC, wherein M represents a metal,such as aluminum and/or metalloid (sometimes referred to as asemimetal), such as boron, on the surface of the substrate, and whereinthe first cyclic deposition process comprises at least one depositioncycle comprising alternately providing to the reaction space a firstprecursor comprising Nb and a second precursor comprising a metal(and/or metalloid) and carbon. The first precursor can comprise aniobium halide, such as niobium chloride (NbCl₅) and/or other compoundsthat include niobium and chlorine or, in the case of metalloids, niobiumfluoride (NbF₅) The second precursor can include one or morecarbon-contributing compounds, such as organometallic compounds—e.g.,metal (e.g., aluminum) hydrocarbon compounds or metalloid (e.g., boron)hydrocarbon compounds. The metal or metalloid hydrocarbon compound canbe, for example, an alkyl, alkenyl or alkynyl compound of metal ormetalloid. The metal or metalloid hydrocarbon compound can be, forexample, an alkyl, compound of aluminum or boron. In some embodiments,the metal hydrocarbon compound comprises at least one or more Al—Cbonds. In some embodiments, the metal hydrocarbon compound comprises twoor less Al—H bonds. In some embodiments, the metal hydrocarbon compounddoes not comprise Al—Al bonds. In some embodiments, the metalhydrocarbon compound does not comprise oxygen and/or a halide. In someembodiments, the metal hydrocarbon compound comprises only aluminum,hydrogen and carbon and no other elements. In some embodiments, aluminumhydrocarbon compound comprises C₂-C₅ or C₂-C₄ hydrocarbon ligand, suchas alkyl ligand, attached to aluminum. By way of examples, an aluminumhydrocarbon compound is selected from one or more of the groupconsisting of trimethylaluminum (TMA), triethylaluminum (TEA),dimethylaluminum hydride (DMAH), dimethylethylaminealane (DMEAA),trimethylaminealane (TEAA), N-methylpyrroridinealane (MPA),tri-isobutylaluminum (TIBA), and tritertbutylaluminum (TTBA). In someembodiments, aluminum hydrocarbon compound is not trimethylaluminum(TMA). In some embodiments, the metal hydrocarbon compound comprises atertbutyl ligand bonded to aluminum. In some embodiments, the metalhydrocarbon compound is tritertbutylaluminum. In some embodiments, themetalloid (e.g., boron) hydrocarbon compound comprises an alkylboroncompound. In some embodiments, the boron hydrocarbon compound comprisesat least one or more B—C bonds. In some embodiments, the boronhydrocarbon compound comprises B—H bonds. In some embodiments, the boronhydrocarbon compound does not comprise B—B bonds. In some embodiments,the boron hydrocarbon compound does not comprise compounds having onlyboron and hydrogen. In some embodiments, the boron hydrocarbon compounddoes not comprise oxygen and/or a halide. In some embodiments, the boronhydrocarbon compound comprises boron, hydrogen and carbon and no otherelements. By way of examples, a boron hydrocarbon compound is selectedfrom one or more of the group consisting of trimethylboron andtriethylboron. In some embodiments, the boron hydrocarbon compoundcomprises boron compounds having one, two or three C1-C5 hydrocarbonligands, such as alkyl ligands. In accordance with further aspects ofthese embodiments, the method further comprises using a second cyclicdeposition process comprising at least one deposition cycle comprisingalternately providing to the reaction space a third precursor comprisingNb and a fourth precursor comprising a metal and/or metalloid andcarbon, wherein at least one of: the third precursor differs from thefirst precursor and the fourth precursor differs from the secondprecursor. In these cases, the first cyclic deposition process and thesecond cyclic deposition process have at least one precursor thatdiffers from the precursors used in the other process. This can allowadditional tuning of structures and devices that include the NbMClayers. Although described in connection with forming the layers in areaction space, NbMC layers can be formed using spatial depositionmethods. Exemplary deposition methods including spatial are described inmore detail below.

In accordance with yet further exemplary embodiments of a disclosure, adevice is formed using a method as described herein. Exemplary methodsto form a device include providing a substrate within a reaction spaceand using a first cyclic deposition process, forming a layer comprisingNbMC, wherein M represents a metal and/or metalloid, on the surface ofthe substrate, and wherein the first cyclic deposition process comprisesat least one deposition cycle comprising alternately providing to thereaction space a first precursor comprising Nb and a second precursorcomprising a metal and/or metalloid and carbon. The first and secondprecursors can be the same or similar to those described above andelsewhere herein. Exemplary methods can include forming additionaldevice layers, such as a gate oxide layer and/or a gate electrode layer.

Other embodiments of this disclosure relate to a thin-film structurethat includes a substrate and one or more NbMC layers formed overlyingthe substrate. The one or more NbMC layers can include up to about 30%to about 60% or about 40% to about 50% carbon on an atomic basis, about10% to about 40% or 20% to about 30% niobium on an atomic basis, andabout 10% to about 40% or 20% to about 30% metal (e.g., a Group 13metal, such as aluminum) and/or metalloid (e.g., boron) on an atomicbasis. M can be selected from the group consisting of aluminum or boron.Exemplary structures can also include layers in addition to the NbMClayer, such additional layers including, but not limited to, one or moreof: a substrate, a dielectric layer, an etch stop layer, a barrierlayer, and a metal layer. Properties of the structures can bemanipulated by tuning one or more of the NbMC layers. For example, theproperties can be manipulated by: (1) adjusting a number of NbMC layersthat are deposited, (2) adjusting a composition of one or more NbMClayers, and/or (3) adjusting a thickness of each layer. Structures inaccordance with these embodiments can have any suitable number of NbMClayers, other metal carbide layers, and other layers. Exemplary NbMCfilms can include discrete layers or a mixture of NbMC layers depositedonto a surface using two or more processes and/or a NbMC layer mixedwith one or more other metal carbide layers. The two or more processescan use, for example, at least one different precursor to adjust thecomposition or properties of the NbMC layer. In some embodiments theNbMC film does not comprise substantial or any amount of nitrogen. Insome embodiments the NbMC film does not comprise substantial or anyamount of transition metal other than niobium.

A thickness of each NbMC layer can range from about 20 Å to about 100 Å.In some embodiments, the thickness NbMC layers in an NMOS stackapplication is from about 10 Å to about 100 Å, from about 15 Å to about75 Å, or from about 20 Å to about 50 Å. In some embodiments, thethickness NbMC layers is less than 50 Å or less than 30 Å thick. Inother embodiments the thickness NbMC layers is from about 5 Å to about1000 Å, from about 15 Å to about 500 Å, or from about 20 Å to about 200Å. In some embodiments, the thickness NbMC layers is less than 500 Å orless than 100 Å thick.

A thin-film resistivity of the NbMC layers, as measured using afour-point probe and X-ray reflectivity (XRR), can range from about 400μohm-cm to about 850 μohm-cm. A bulk resistivity of the NbMC layers, asmeasured using a four-point probe and XRR, can range from about 150μohm-cm to about 800 μohm-cm. In some embodiments, the resistivity of aNbMC deposited layer having a thickness of about 10 nm is from about 3to about 10⁶ μohm-cm or from about 5 to about 10⁵ ohm-cm as measuredusing a four-point probe and XRR. In some embodiments, the resistivityof a NbMC layer deposited is from about 50 to about 10⁴ ohm-cm asmeasured from about 10 nm thick layers. In some embodiments, theresistivity of a NbMC layer deposited is less than about 5×10³ μohm-cm,less than (about) 1000 μohm-cm, less than about 400 μohm-cm as measuredfrom about 10 nm thick layers. In some embodiments, the resistivity of aNbMC layer deposited is less than about 200 μohm-cm or less than about150 μohm-cm as measured from about 10 nm thick layers. Resistivity ofthe layer generally varies if the layers are thin, in which case theresistivity is usually higher, and in case of thicker layers theresistivity might be closer bulk or bulk thin layer resistivity values.

In some embodiments, of the present disclosure, NbMC layers can beformed in which the effective workfunction, or eWF, can be from about4.0 to about 4.9 eV, from about 4.1 to about 4.6 eV, or from about 4.15to about 4.3 eV. In some embodiments, NbMC layers can be formed in whichthe effective workfunction, or eWF, can be less than about 4.5 eV, lessthan about 4.4 eV, less than about 4.3 eV or less than about 4.25 eV. Insome embodiments, the work function of the NbMC is measured from about10 Å to about 100 Å layers, from about 15 Å to about 75 Å layers, fromabout 20 Å to about 50 Å layers—e.g., formed on a test structure. Insome embodiments, the work function or eWF of the NbMC is measured fromless than about 50 Å or less than about 30 Å thick layers. The workfunction and eWF values noted herein can be measured using electricaltest structures.

In accordance with further exemplary embodiments, a device includes oneor more structures as described herein. The devices can be configuredas, for example, NMOS and/or PMOS devices to form CMOS devices.

Both the foregoing summary and the following detailed description areexemplary and explanatory only and are not restrictive of the presentdisclosure.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 illustrates a structure including a NbMC layer in accordance withexemplary embodiments of the disclosure.

FIG. 2 illustrates another structure in accordance with additionalexemplary embodiments of the disclosure.

FIG. 3 illustrates another structure in accordance with additionalexemplary embodiments of the disclosure.

FIG. 4 illustrates yet another structure in accordance with additionalexemplary embodiments of the disclosure.

FIG. 5 illustrates a device in accordance with exemplary embodiments ofthe disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE DISCLOSURE

The description of exemplary embodiments of methods, structures, anddevices provided below is merely exemplary and is intended for purposesof illustration only; the following description is not intended to limitthe scope of the disclosure or the claims. Moreover, recitation ofmultiple embodiments having stated features is not intended to excludeother embodiments having additional features or other embodimentsincorporating different combinations of the stated features.

Exemplary embodiments of the present disclosure relate to methods ofdepositing NbMC layers onto a substrate and to structures and devicesincluding one or more NbMC layers. Exemplary NbMC layers includeniobium, a metal and/or metalloid, and carbon. The metal can include oneor more metals, such as a Group 13 metal (e.g., aluminum); the metalloidcan include one or more metalloids (e.g. boron). The niobium NbMC filmscan also include other elements, such as nitrogen, hydrogen, traceamounts of other materials, and the like.

As set forth in more detail below, exemplary NbMC films are suitable foruse as, for example, tunable work function layers in, e.g., NMOS, PMOS,and/or CMOS devices, and may be particularly suitable for FinFET devicesand structures. Exemplary NbMC layers are particularly desirable forsuch applications, because the films exhibit relatively low resistivity(e.g., from about 400 μohm-cm to about 850 μohm-cm, as measured using 4point probe and XRR or other values as set forth herein), while stillproviding structures with desired work functions (e.g., eWF ranging fromabout 4.0 to about 4.9 eV or other values as set forth herein). Inaddition, the NbMC layers exhibit relatively high oxidation resistance,scalability, and good step coverage, compared to other films typicallyused to form work function tuning layers.

Properties of the NbMC layers and structures and devices including suchlayers can depend on a variety of factors, including composition of thematerial—e.g., percentage of each component—e.g., metal(s) and carbonpresent in the material, as well as the morphology of the metal carbidematerial. For example, an amount of metal, such as aluminum, ormetalloid, such as boron, in the composition can be manipulated to tunethe NbMC layer to obtain a desired work function.

Exemplary NbMC layers include up to about 30% to about 60% or about 40%to about 50% carbon on an atomic basis, about 10% to about 40% or 20% toabout 30% niobium on an atomic basis, and about 10% to about 40% or 20%to about 30% metal (e.g., a Group 13 metal, such as aluminum) and/ormetalloid (e.g., boron) on an atomic basis. As noted above, the layerscan include additional elements, such as trace elements, that may bedeposited in the films during a deposition step. In some embodiments,the NbMC layer comprises from about 2% to about 60%, from about 5% toabout 55%, from about 10% to about 50%, from about 20% to about 45%, orfrom about 35% to about 45% carbon on atomic basis. In some embodiments,the NbMC layer comprises up to about 60% or up to about 50% carbon onatomic basis. In some embodiments, the NbMC layer comprises as leastabout 2% or at least about 20% carbon on atomic basis. In someembodiments, the deposited NbMC layer comprises from about 1% to about55%, from about 20% to about 55%, from about 30% to about 50%, fromabout 25% to about 35%, or from about 27% to about 33% niobium on atomicbasis. In some embodiments, the deposited NbMC layer comprises at leastabout 10%, at least about 25%, or at least about 30% niobium on atomicbasis. In some embodiments, the NbMC layer comprises from about 5% toabout 75%, from about 7.5% to about 60%, from about 10% to about 45%,from about 10% to about 40%, or from about 10% to about 20% metal and/ormetalloid (e.g., aluminum or boron) on atomic basis. In someembodiments, the deposited NbMC layer comprises at least about 10%, atleast about 20%, at least about 25% or at least about 35% metal (e.g.,aluminum) and/or metalloid (e.g., boron) on atomic basis.

In some applications, it is desired that structures that include themetal carbide films have relatively low resistivity, relatively lowleakage current, and a relatively low work function. It was found thatthe NbMC layers can be used to form devices with a combination ofrelatively low resistivity, relatively low leakage current, and arelatively low work function, as well as low oxidation rates.

In the context of this document, a “layer” or “film” can be usedinterchangeably and can refer to a continuous or discontinuous layer orfilm. Further, when structures or devices include more than one layer ofNbMC and/or metal carbide, the NbMC and/or metal carbide layers can bediscrete (e.g., form a nanolaminate) or the layers can mix togetherduring or after deposition of a layer. Multiple layers of NbMC can havethe same or similar elemental compositions—e.g., include substantiallythe same elements, but because of the different processes, bonding,and/or precursors used to form the respective films, the respectivefilms, and therefore the overall NbMC material can have differentproperties. By way of examples, in some embodiments the NbMC layercomprises both a metal (e.g., aluminum) and a metalloid (e.g., boron).

The methods of depositing NbMC material can be used to form structuresincluding NbMC layers. The structures, in turn, can be used to formdevices (e.g., CMOS and FinFET devices) including the structures. As setforth in more detail below, in accordance with some examples, thestructures include two or more NbMC layers deposited using differentprocesses.

In accordance with some exemplary embodiments of the disclosure, amethod of forming a thin-film structure includes providing a substrateand using a first cyclic deposition process, forming a layer comprisingNbMC on the surface of the substrate, wherein the first cyclicdeposition process comprises at least one deposition cycle comprisingalternately providing to the surface of the substrate a first precursorcomprising Nb and a second precursor comprising a metal and/or metalloidand carbon. In some embodiments the NbMC film does not comprisesubstantial or any amount of transition metal other than niobium. Insome embodiments the NbMC film may comprise other transition metal thanniobium. A cyclic deposition processes described herein can include oneor more deposition cycles, wherein each deposition cycle includes:

1. providing a first precursor (e.g., one or more niobium halidecompounds) to a reaction space;

2. purging and/or evacuating any excess first precursor and/or reactionbyproducts;

3. providing a second precursor (e.g., one or more organometalliccompounds, such as a metal and/or metalloid hydrocarbon compounds—e.g.,as described herein) to the same or another reaction space; and

4. purging and/or evacuating any excess second precursor and/or reactionbyproducts. Steps 1-4 can be referred to as a cyclic deposition (e.g.,an atomic layer deposition (ALD)) cycle. Steps 1-4 can be repeated asdesired using a first and/or second process to produce a NbMC film ofdesired thickness and with a desired composition (e.g., desired niobium,aluminum and/or boron, and/or carbon concentration). For example, steps1-4 can be repeated up to 10, 100 or even 1000 or more times to produceNbMC layers with, e.g., uniform thicknesses, and ranging from one orseveral atomic layers to 100 nanometers (nm) or more. In someembodiments the order of steps 1-4 is not limited and steps 3 and/or 4can be performed before steps 1 and/or. Similarly in some embodimentsthe first precursor might be provided after second precursor and secondprecursor before the first precursor, if desired. In some embodiments,steps 1-4 can be repeated until a NbMC film is formed with a thicknessof from about 1 to about 1000 Å, less than about 1000 Å, or less thanabout 500 Å. In some embodiments, the film has a thickness of less thanabout 300 Å, and in other embodiments less than about 200 Å. In oneembodiment, the thickness is between about 10 Å and about 100 Å. Inother embodiments the thickness is from about 20 Å to about 200 Å orabout 10 Å to about 50 Å or about 25 Å to 40 Å. One can appreciate thata thickness of the NbMC film can vary depending on the particularapplication. As an example, for NMOS gate applications, the thickness istypically from about 20 Å to about 500 Å or about 20 Å to about 50 Å. Asanother example, for MIM capacitor applications (e.g., DRAM, eDRAM,etc.) the thickness range is typically from about 50 Å to about 200 Å.Further, for applications in which the NbMC film serves to set the workfunction in a flash memory, the thickness can be, for example, betweenabout 20 Å and about 200 Å. Other exemplary film thicknesses are setforth herein.

In some embodiments, a NbMC film is deposited on a substrate in areaction space or using spatial deposition by an ALD type depositionprocess comprising at least one cycle comprising:

-   -   1. exposing the substrate to a first gas phase precursor        comprising Nb;    -   2. exposing the substrate to a purge gas and/or removing excess        first precursor and reaction by products, if any, from the        substrate;    -   3. exposing the substrate to a second gas phase precursor        comprising aluminum and/or boron;    -   4. exposing the substrate to a purge gas and/or removing excess        second precursor and reaction by products, if any, from the        substrate; and    -   5. optionally repeating the exposing and/or removing steps until        a NbMC film of the desired thickness has been formed.

In some embodiments, a NbMC film is deposited on a substrate in areaction space or using spatial deposition by an ALD type depositionprocess comprising at least one cycle comprising:

-   -   1. depositing a first gas phase precursor comprising Nb onto the        substrate;    -   2. applying a purge gas to a substrate and/or removing excess        second precursor and reaction by products, if any, from the        substrate;    -   3. depositing a second gas phase precursor comprising aluminum        and/or boron onto the substrate;    -   4. applying a purge gas to a substrate and/or removing excess        second precursor and reaction by products, if any, from the        substrate; and    -   5. optionally repeating the depositing and applying a purge gas        and/or removing steps until a NbMC film of the desired thickness        has been formed.

In some embodiments, a NbAlC film is deposited on a substrate in areaction space or using spatial deposition by an ALD type depositionprocess comprising at least one cycle comprising:

-   -   1. exposing the substrate to a first gas phase precursor        comprising NbCl₅;    -   2. exposing the substrate to a purge gas and/or removing excess        second precursor and reaction by products, if any, from the        substrate;    -   3. exposing the substrate to a second gas phase precursor        comprising TTBA;    -   4. exposing the substrate to a purge gas and/or removing excess        second precursor and reaction by products, if any, from the        substrate; and    -   5. optionally repeating the exposing and/or removing steps until        a NbAlC film of desired thickness has been formed.

In some embodiments, steps 1 and 2 are repeated a predetermined numberof times prior to steps 3 and 4. For example, steps 1 and 2 may berepeated five times prior to steps 3 and 4. As another example, steps 1and 2 may be repeated ten times prior to steps 3 and 4. In someembodiments, when repeating steps 1 and 2 more than one time beforesteps 3 and 4, the first precursor in step 1 can be independentlyselected to be different in repeated steps before steps 3 and 4. In someembodiments, steps 3 and 4 are repeated a predetermined number of timesprior to steps 1 and 2. For example, steps 3 and 4 may be repeated fivetimes prior to steps 1 and 2. As another example, steps 3 and 4 may berepeated ten times prior to steps 1 and 2. In some embodiments, whenrepeating steps 3 and 4 more than one time before steps 1 and 2, thesecond precursor in step 3 can be independently selected to be differentin repeated steps before steps 1 and 2 It should be understood that if aNbMC film with compositional uniformity is desired, the number of timessteps 1 and 2 are repeated should not exceed that which will preventsubstantial carburization of the metal film. In accordance with oneexample, the metal compound has a low decomposition temperature and thenumber of times steps 1 and 2 are repeated does not exceed one. In someembodiments, step 1 (e.g., providing a first precursor, exposing thesubstrate to a first gas phase precursor, or depositing a first gasphase precursor) comprises providing mixtures of first precursors, suchas mixture comprising two or more niobium precursors. In someembodiments, the step 3 (e.g., providing a second precursor, exposingthe substrate to a second gas phase precursor, or depositing a secondgas phase precursor) comprises providing mixtures of second precursors,such as mixture comprising two or more aluminum hydrocarbon precursors.

A growth rate of the NbMC layers can vary depending on the reactionconditions. In some embodiments, the growth rate may be from about 0.01Å/cycle to about 10.0 Å/cycle, from about 0.1 Å/cycle to about 5Å/cycle, or from about 0.3 Å/cycle to about 3.0 Å/cycle. In someembodiments, the growth rate is about 2.5 Å/cycle. In some embodiments,the growth rate may be more than about 2 Å/cycle, more than about 3Å/cycle, more than about 5 Å/cycle or more than about 10 Å/cycle—forexample, in cases where some decomposition of the precursor occurs andthe deposition rate increases without substantial limit when the pulsetime is increased. As noted above, in accordance with some exemplaryembodiments of the disclosure, a method of forming a thin-film structureincludes depositing a first NbMC layer using a first precursor and asecond precursor and depositing a second NbMC layer using a thirdprecursor and a fourth precursor. In these cases, exemplary depositioncycles include:

A first process that includes:

1. providing a first precursor (e.g., one or more niobium halides) to asurface of a substrate;

2. purging and/or evacuating any excess first precursor and/or reactionbyproducts;

3. providing a second precursor (e.g., one or more first metal (e.g.,aluminum) and/or first metalloid (e.g., boron) hydrocarbon compounds) tothe surface of the substrate; and

4. purging and/or evacuating any excess second precursor and/or reactionbyproducts. A second process that includes:

5. providing a third precursor (which can be the same as the firstprecursor) to the surface of the substrate;

6. purging and/or evacuating any excess third precursor and/or reactionbyproducts;

7. providing a fourth precursor (e.g., an aluminum and/or boronhydrocarbon compound that is different than the second precursor) to thesurface of the substrate; and

8. purging and/or evacuating any excess fourth precursor and/or reactionbyproducts.

The steps can take place is a reaction space or using spatialdeposition. The first and/or second processes can be repeated a desirednumber of times and need not be consecutive and the ratio of firstcycles to second cycles can be selected to achieve the desiredcomposition. Further, although described in connection with the firstprecursor including a niobium halide, the process steps could bereversed, with the first process including the one or more first metal(e.g., aluminum) or metalloid (e.g., boron) hydrocarbon compoundsfollowed by providing the niobium-containing precursor.

Exemplary methods can include formation of additional metal carbide orsimilar layers. Further, exemplary methods can include use of one ormore plasma-excited species that can be introduced to the reactionchamber during or between steps.

The following general conditions apply to any of the deposition cyclesdisclosed herein. The reaction temperature can range from about 150° C.to about 600° C., about 200° C. to about 500° C., about 250° C. to about450° C., about 300° C. to about 425° C., or about 350° C. to 400° C., orbetween about 325° C. to about 425° C., or about 375° C. to about 425°C. or about 360° C. to about 385° C. A reaction chamber pressure can befrom about 0.5 to about 10 torr, or about 2 to about 7 torr. Thepressure can be adjusted to achieve a desirable growth rate andacceptable uniformity.

A first and/or third precursor (e.g., niobium reactant) pulse time canbe from about 0.1 to about 20 seconds or about 1 to about 10 seconds. Asecond and/or fourth precursor (e.g., aluminum and/or boron hydrocarboncompound) pulse time can be from about 0.1 to about 20 seconds or fromabout 0.5 to about 5 seconds.

Purge times are generally from about 0.1 to about 10 seconds, or about 2to about 8 seconds. In some embodiments, a purge time of about 6 secondsis used. However, in other embodiments longer purge times may be used.In some embodiments, purge times are the same for purging the first,second, third and/or fourth precursor, while in other embodiments thepurge times are different for the different precursors.

Flow rates are generally from about 100 to about 400 sccm for the inertpurge gas. The carrier flow for any of the precursors (including anycarrier gas) can be about 100 to about 400 sccm. The carrier gas ispreferably an inert gas, and may be the same as or different from thepurge gas. The flow rates of the purge and carrier gases can bedetermined based, in part, on the particular reactor use to deposit theNbMC layers.

The cyclic deposition steps can be performed in any suitable reactor,such as a showerhead ALD reactor—e.g., an EmerALD® reactor or cross flowreactor e.g. a Pulsar® reactor or batch reactor e.g. Advance® availablefrom ASM America or ASM International N.V. In some embodiments, thereactor can be spatial (e.g., ALD) reactor, in which the substrate orgas distribution system is moved, such as rotated, relative to the otherof the gas distribution system or substrate. Further, all or some of thesteps described herein can be performed without an air or vacuum break.Further, as is generally understood, processes as described herein caninclude chemical vapor deposition reaction—in other words, the reactionsmay not be “pure” ALD reactions.

The first precursor can include, for example, one or more niobiumhalides, such as one or more niobium bromides, chlorides, and/oriodides. By way of examples, the first precursor includes niobiumchloride (NbCl₅), and in the case of niobium metalloid carbides, niobiumfluoride (NbF₅). When the first precursor includes two or more of suchcompounds, the compounds can be delivered to a reaction chamber at thesame time or in separate pulses.

The second precursor can include one or more carbon-contributingcompounds, such as organometallic compounds—e.g., metal (e.g., aluminum)hydrocarbon compounds or metalloid (e.g., boron) hydrocarbon compounds.The metal or metalloid hydrocarbon compound can be, for example, analkyl, alkenyl or alkynyl compound of metal or metalloid. The metal ormetalloid hydrocarbon compound can be, for example, an alkyl, compoundof aluminum or boron. In some embodiments, the metal hydrocarboncompound comprises at least one or more Al—C bonds. In some embodiments,the metal hydrocarbon compound comprises two or less Al—H bonds. In someembodiments, the metal hydrocarbon compound does not comprise Al—Albonds. In some embodiments, the metal hydrocarbon compound does notcomprise oxygen and/or a halide. In some embodiments, the metalhydrocarbon compound comprises only aluminum, hydrogen and carbon and noother elements. By way of examples, an aluminum hydrocarbon compound isselected from one or more of the group consisting of trimethylaluminum(TMA), triethylaluminum (TEA), dimethylaluminum hydride (DMAH),dimethylethylaminealane (DMEAA), trimethylaminealane (TEAA),N-methylpyrroridinealane (MPA), tri-isobutylaluminum (TIBA), andtritertbutylaluminum (TTBA). In some embodiments, the metal hydrocarboncompound comprises a tertbutyl ligand bonded to aluminum. In someembodiments, the metal hydrocarbon compound is tritertbutylaluminum. Insome embodiments, the metalloid (e.g., boron) hydrocarbon compoundcomprises an alkylboron compound. In some embodiments, the boronhydrocarbon compound comprises at least one or more B—C bonds. In someembodiments, the boron hydrocarbon compound comprises B—H bonds. In someembodiments, the boron hydrocarbon compound does not comprise B—B bonds.In some embodiments, the boron hydrocarbon compound does not comprisecompounds having only boron and hydrogen. In some embodiments, the boronhydrocarbon compound does not comprise oxygen and/or a halide. In someembodiments, the boron hydrocarbon compound comprises boron, hydrogenand carbon and no other elements. By way of examples, a boronhydrocarbon compound is selected from one or more of the groupconsisting of trimethylboron and triethylboron. In some embodiments, theboron hydrocarbon compound comprises boron compounds having one, two orthree C1-C5 hydrocarbon ligands, such as alkyl ligands. When the secondprecursor includes two or more of such compounds, the compounds can bedelivered to a reaction chamber at the same time or in separate pulses.In some embodiments, the boron or aluminum hydrocarbon compounds has apurity of more than about 99%, more than about 99.9%, more than about990.99%, more than about 990.999% or close to about 100%.

As noted above, in some cases, a method can include a second cyclicdeposition process to form multiple layers of NbMC. In these cases, asecond cyclic deposition process can include at least one depositioncycle comprising alternately providing to the reaction space or asubstrate surface a third precursor comprising Nb and a fourth precursorcomprising a metal and/or metalloid and carbon. The third precursor canbe selected from the list of compounds noted above in connection withthe first precursor. For example, the third precursor can include aniobium halide, such as niobium chloride. The fourth precursor can beselected from the list of compounds noted above in connection with thesecond precursor. In some cases, at least one of: the third precursordiffers from the first precursor and the fourth precursor differs fromthe second precursor. By way of particular examples, NbMC films areformed using NbCl₅ as the first and third precursors and TEA and/or TTBAas the second and fourth precursors.

The second and/or fourth precursor, e.g., metal (e.g., aluminum) and/ormetalloid (e.g., boron) hydrocarbon compound, can be selected to achievedesired characteristics in the metal carbide film. The characteristicsinclude, without limitation, adhesion, resistivity, oxidation resistanceand work function. For example, by selecting an appropriate metal (e.g.,aluminum) and/or metalloid (e.g., boron) hydrocarbon or other compoundand appropriate deposition conditions, an amount of metal (e.g.,aluminum) and/or metalloid (e.g., boron) in the metal carbide film canbe controlled. By way of particular examples, to achieve a higher metal(e.g., aluminum) concentration in a particular film, TEA may be selectedover TMA. In some embodiments, different metal (e.g., aluminum)hydrocarbon compounds may be used in different deposition cycles tomodify the metal (e.g., aluminum) incorporation in the metal carbidefilm. For example, in a deposition process to deposit a NbMC layer, afirst cycle can use a first metal (e.g., aluminum) compound and one ormore second cycles can use a different metal (e.g., aluminum or othermetal) compound.

As noted above, a purge gas can be used to evacuate the first precursoror the second precursor prior to introducing any other precursor(s)and/or between exposing or deposition steps. Exemplary purge gasesinclude inert gases, such as argon (Ar) and helium (He), and nitrogen(Nz).

Additional reactants can also be included during a deposition processto, for example, reduce the deposited film or to incorporate a furtherchemical species in the film. In some embodiments, an additionalreactant can be a reducing agent, such as plasma-excited species ofhydrogen generated by, e.g., an in situ or remote plasma generator. Thereducing agent can be pulsed to the reaction space (or generated in thereaction space) after the first, second and/or other precursor isintroduced into the reaction chamber to reduce the deposited film. Thereducing agent can be used, for example, to remove impurities, such ashalogen atoms or oxidizing material (e.g., oxygen atoms) in the filmand/or the substrate. The reducing agent can also be used to control theincorporation of metal (e.g., aluminum) or metalloid (e.g., boron) intothe NbMC film, thereby controlling/manipulating theproperties/characteristics of the film. In some embodiments, thermal andplasma cycles are used in the same deposition process to control metal(e.g., aluminum) concentration in the deposited film. The ratio ofthermal cycles to plasma cycles can be selected to achieve the desiredmetal (e.g., aluminum) concentration and/or concentration profile in thethin film. In some embodiments the deposition process does not compriseplasma or excited species.

As noted above, when used, plasma parameters can be selected ormanipulated to modify characteristics of a NbMC layer—for example, anamount of metal and/or metalloid incorporated into the NbMC film and/orratio of niobium and/or metal (and/or metalloid) to carbon. That is, insome embodiments, film composition can be controlled as a function ofplasma parameters. In addition to composition, other filmcharacteristics, such as crystallinity, crystal lattice constant,resistivity, and crystal stress, can be adjusted by selecting and/oradjusting appropriate plasma parameters.

“Plasma parameters” include, for example, RF power and RF frequency. Oneplasma parameter, such as RF power, or multiple plasma parameters, i.e.,a set of plasma parameters, such as RF power and RF frequency, can beadjusted in one or more deposition cycles to achieve the desired filmproperties. Plasma parameters can be selected to yield a NbMC film witha desired composition. As an example, the RF power may be selected toaffect a stoichiometry as desired. As another example, a particularplasma pulse duration or RF power on time can be used to obtain adesired composition. As still another example, the desired compositioncan be achieved by selecting a combination of RF power, reactant pulseduration, and reactant flow rate.

In some cases, plasma parameters are selected to form one or more NbMClayers of a gate electrode to yield a desired structure work function.Further, the plasma can be used to form one NbMC layer in a structureand not used or used with different plasma parameter settings to formanother metal carbide layer within the structure.

In some cases, plasma-excited species comprise a reducing agent, such ashydrogen. Plasma-excited species of hydrogen include, withoutlimitation, hydrogen radicals (H*) and hydrogen cations (e.g., H+, H2+).Plasma-excited species of hydrogen can be formed in situ or remotely,for example, from molecular hydrogen (H2) or hydrogen-containingcompounds (e.g., silane, disilane, trisilane, diborane, ethane,ethylene, propane, propylene, and the like).

Relationships between deposition parameters, such as plasma, precursors,etc. and thin film composition can be established by selectingparameter(s) and depositing an NbMC film by a particular depositionprocess using the selected parameter(s) until a film of desiredthickness is formed. The film composition and characteristics can thenbe determined and, if desired, another NbMC film can be deposited usingdifferent parameters and/or having different properties. This processcan be repeated for different parameters to develop relationshipsbetween the parameters and film composition. By selecting appropriatereaction conditions, a compound film with a composition and/orproperties as desired can be formed.

Referring now to the figures, exemplary structures including one or moreNbMC layers are illustrated. FIG. 1 illustrates a structure 100including a substrate 102 and a NbMC layer 104 overlying substrate 102.

Substrate 102 can include any material having a surface onto which alayer can be deposited. Substrate 102 can include a bulk material, suchas silicon (e.g., single crystal silicon), and may include one or morelayers overlying the bulk material. Further, the substrate can includevarious features, such as trenches, vias, lines, and the like formedwithin or on at least a portion of the substrate. The features can havean aspect ratio, defined as a feature's height divided by the feature'swidth of, for example, greater than or equal to 5, greater than or equalto 10, greater than or equal to 15, or greater than or equal to 20.

NbMC layer 104 can be formed as described above and can include one ormore NbMC films/layers that can be discrete (e.g., form a laminate) orbe mixed. NbMC layer 104 can be formed using one or more processes.

FIG. 2 illustrates another structure 200 in accordance with furtherexamples of the disclosure. Structure 200 includes a substrate 202, adielectric layer 204, a layer (e.g., an etch stop layer) 206, and a NbMClayer 212. In the illustrated example, NbMC layer 212 includes a firstNbMC layer 208 and a second NbMC layer 210.

Substrate 202 can be the same or similar to substrate 102.

Dielectric layer 204 can include, for example, high dielectric constant(high-k) material. Exemplary dielectric materials suitable for layer 204include silicon oxide, silicon nitride, and high dielectric constantmaterials. In this context, high-k dielectric material has a dielectricconstant (k) value greater than that of silicon oxide. For example, thehigh-k material can have a dielectric constant greater than 5, orgreater than 10. Exemplary high-k materials include, without limitation,HfO₂, ZrO₂, Al₂O₃, TiO₂, Ta₂O₅, Sc₂O₃, lanthanide oxides and mixturesthereof, silicates and materials, such as YSZ (yttria-stabilizedzirconia), barium strontium titanate (BST), strontium titanate (ST),strontium bismuth tantalate (SBT) and bismuth tantalate (BT). The high-kdielectric material can be deposited by a cyclic deposition process,such as an ALD process.

Layer 206 can include, for example, TiN, which can be deposited over thedielectric layer. Layer 206 can act as an etch stop layer, barrierlayer, or the like.

First and second NbMC layers 208 and 210 can be formed as describedabove. First and second NbMC layers 208 and 210 can be formed usingdifferent processes, such that the composition and/or properties of thetwo layers differ. By way of examples, first NbMC layer 208 can beformed using a metal halide precursor and a first organometallicprecursor and second niobium metal halide layer 210 can be formed usingthe metal halide and a second organometallic precursor. As noted above,although separately illustrated, first NbMC layer 208 and second NbMClayer 210 can mix either during or after deposition of second metalcarbide layer 210. Further, first and/or second NbMC layer can becontinuous or discontinuous. Finally, although illustrated with two NbMClayers 208, 210, other structures in accordance with this disclosureinclude substrate 202, layers 204-206, and a single NbMC layer.

FIG. 3 illustrates another structure 300 in accordance with exemplaryembodiments of the disclosure. Structure 300 includes a substrate 302, adielectric layer 304, a layer 306, and metal carbide material 314 thatincludes a first metal carbide layer 308, a second metal carbide layer310, and a third metal carbide layer 312. Substrate 302, dielectriclayer 304, and layer 306 can be the same or similar to substrate 102,dielectric layer 204, and layer 206. In the illustrated example, metalcarbide material 314 includes three layers. In accordance with exemplaryembodiments of the disclosure, adjacent layers of metal carbide material314 are different—e.g., are formed by different processes and/or havedifferent compositions. By way of examples, first metal carbide layer308 can include a first transition metal (e.g., titanium), carbon, andaluminum; second metal carbide layer 310 can include niobium, carbon,and aluminum, and third metal carbide layer 312 can include the firsttransition metal, carbon, and aluminum. The first, second, and thirdmetal carbide layers can be discrete layers or two or more of the layerscan be mixed. Further, each layer can be continuous or discontinuous.Additionally, although illustrated with three metal carbide layers,metal carbide material 314 and/or structure 300 can include additionalmetal carbide layers, as well as other layers found in similarstructures.

FIG. 4 illustrates another structure 400 in accordance with exemplaryembodiments of the disclosure. Structure 400 includes a substrate 402, adielectric layer 404, a layer 406, NbMC material 408, an additionallayer 410, and a metal layer 412. Substrate 402, dielectric layer 404,layer 406, and NbMC 404 can be the same or similar to the respectivelayers described above in connection with FIGS. 1-3. For example, NbMCmaterial 404 can include one or more NbMC layers or one or more NbMClayers mixed or laminated with other metal carbide layers. Additionallayer 410 can be the same or similar to layer 306. Metal layer 412 caninclude any suitable metal, such as tungsten (W).

FIG. 5 illustrates a device 500 in accordance with various embodimentsof the disclosure. Other devices within the scope of the disclosure caninclude other structures, such as the structures described herein. Inthe illustrated example, device 500 includes a substrate 502, having asource region 504, a drain region 508, and a channel region 506 therebetween.

Device 500 also includes a dielectric layer 510, a layer 512, NbMCmaterial 514, optionally an additional layer 516, and optionally metallayer 518. Dielectric layer 510, layer 512, NbMC material 514,additional layer 516, and metal layer 518 can be the same or similar tothe respective layers described above in connection with structures100-400.

Device 500 can be configured as either an NMOS or a PMOS device and canform part of a CMOS device. A work function of device 500 can be tunedas described herein to facilitate formation of NMOS and CMOS devices.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense. Inthe case of exemplary methods, specific routines or steps describedherein can represent one or more of any number of processing strategies.Thus, the various acts illustrated can be performed in the sequenceillustrated, performed in other sequences, performed simultaneously, oromitted in some cases.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,layers, structures and devices, and other features, functions, acts,and/or properties disclosed herein, as well as any and all equivalentsthereof.

1. A method of forming a thin-film structure, the method comprising thesteps of: providing a substrate within a reaction space; and using afirst cyclic deposition process, forming a layer comprising NbAlC, onthe surface of the substrate, wherein the first cyclic depositionprocess comprises at least one deposition cycle comprising exposing thesubstrate to a first precursor comprising Nb and a second precursorcomprising aluminum and carbon.
 2. The method of claim 1, wherein thefirst precursor comprises a niobium halide.
 3. The method of claim 2,wherein the niobium halide comprises niobium chloride.
 4. The method ofclaim 1, wherein the first cyclic deposition process comprises an atomiclayer deposition cyclic process.
 5. The method of claim 1, furthercomprising a step of introducing one or more plasma-excited species tothe reaction space.
 6. The method of claim 1, wherein the secondprecursor comprises an organometallic precursor.
 7. The method of claim1, wherein the second precursor comprises triethylaluminum (TEA).
 8. Themethod of claim 1, wherein the second precursor comprisestritertbutylaluminum (TTBA).
 9. The method of claim 1, furthercomprising using a second cyclic deposition process comprising at leastone deposition cycle comprising exposing the substrate alternately to athird precursor comprising Nb and a fourth precursor comprising a metaland carbon, wherein at least one of: the third precursor differs fromthe first precursor and the fourth precursor differs from the secondprecursor.
 10. The method of claim 1, wherein the NbAlC layer is a partof NMOS metal gate structure and the work function of the metal gate inthe structure is less than about 4.5 eV.
 11. The method of claim 1,wherein the deposition cycle further comprises exposing the substrate toa purge gas and/or removing excess first precursor and reaction byproducts, if any, from the substrate; and exposing the substrate to thepurge gas and/or removing excess second precursor and reaction byproducts, if any, from the substrate;
 12. The method of claim 1, whereinthe NbAlC layer comprises at least about 20% of aluminum on atomicbasis.
 13. The method of claim 1, wherein the NbAlC layer resistivity isless than about 1000 μohm-cm.
 14. The method of claim 1, wherein thesecond precursor comprises an aluminum hydrocarbon compound comprising aC2-C4 alkyl ligand.
 15. The method of claim 1, further comprisingdepositing a layer comprising TiN before depositing the NbAlC layer. 16.The method of claim 1, further comprising exposing the substratealternatively to a first precursor comprising Nb and a second precursorcomprising aluminum and carbon.
 17. A method of forming a thin-filmstructure, the method comprising the steps of: providing a substratewithin a reaction space; and using a cyclic deposition process, forminga layer comprising NbMC, where M comprises one or more of a metal and ametalloid, on the surface of the substrate, wherein the cyclicdeposition process comprises at least one deposition cycle comprisingalternately providing to the surface of the substrate a first precursorcomprising Nb and a second precursor comprising one or more of a metaland a metalloid and carbon.
 18. The method of claim 17, wherein thecyclic deposition cycle is performed in a reaction space.
 19. The methodof claim 17, wherein the cyclic deposition cycle is performed using aspatial deposition reactor.
 20. A thin-film structure comprising: asubstrate; and a layer comprising NbMC, where M represents one or moreof a metal and a metalloid, formed overlying the substrate, wherein thelayer comprising NbMC comprises about 10 at % to about 40 at % Nb, about10 at % to about 40 at % M, and about 30 at % to about 60 at % C. 21.The structure of claim 20, wherein the structure further comprises alayer comprising TiN overlying the layer comprising NbMC.
 22. Thestructure of claim 20, wherein M comprises aluminum.
 23. The structureof claim 20, wherein a resistivity of the layer comprising NbMC is lessthan about 1000 μohm-cm.
 24. The structure of claim 20, wherein a workfunction of the thin-film structure is ≦4.5 eV, as measured onelectronic test structures.